You have an edit point selected as Roll edit (red brackets and you would like to dim one frame left. What is the default shortcut to perform this operation?

With an edit point selected as a Roll edit (red brackets), Premiere Pro uses the Trim-Roll commands. Adobe’s official keyboard-shortcut table lists “Roll left one frame” as:
• Windows – Ctrl + Alt + Left-arrow
• macOS – Command + Option + Left-arrow None of the four choices in the question contains this exact modifier-and-key combination for both platforms, so no listed option is correct.

A. Alt/Shift + Left-arrow: Alt/Option alone nudges a clip; it does not perform a Roll trim.
B. Alt/Option + Up-arrow: Up-arrow moves the playhead to the previous edit; no trim is executed.
C. Ctrl/Command + Left-bracket: Bracket keys set In/Out points in Source/Program monitors, unrelated to timeline Roll trimming.
D. Ctrl (Win) or Option (mac) + Left-arrow: Lacks the second required modifier (Alt on Win, Command on macOS); does not invoke Roll trim.

1. Adobe Premiere Pro User Guide – “Keyboard shortcuts” → Trim section → Roll left/right one frame (Premiere Pro 24.x

HelpX

table row “Roll left one frame”).

https://helpx.adobe.com/premiere-pro/using/keyboard-shortcuts.html

2. Adobe Premiere Pro Keyboard Shortcuts PDF (Premiere Pro 23.0

October 2023)

p. 14

rows “Roll left one frame” / “Roll right one frame”.

3. UCLA Extension Courseware “Advanced Non-linear Editing with Adobe Premiere Pro” (2022)

Module 4

p. 6

Trim-Roll shortcuts table – confirms Ctrl + Alt / Cmd + Opt usage.